Salivary function after pediatric bone marrow transplantation

Abstract

Salivary gland dysfunction is one of the oral long-term complications that most affect the quality of life among long-term survivors after treatment for malignant diseases.

The aims of the studies in this thesis were to examine the effect of pediatric bone marrow transplantation (BMT) conditioning regimens on salivary function, caries-associated microflora, and development of dental caries; define risk factors of salivary dysfunction; evaluate subjective xerostomia; and study functional disturbances in the major salivary glands using salivary gland scintigraphy (SGS).

Children treated with BMT before 12 years of age participated in a 4-year prospective longitudinal study. Stimulated whole salivary secretion rate (SSSR) was measured before BMT, at 3, 6, and 12 months after treatment, and then at yearly controls. The results were compared with those of a reference group of children stratified for age and sex. A multivariate logistic regression analysis of 40 possible risk factors for salivary dysfunction--defined as an SSSR = 0.5 ml/min-was made I year after pediatric BMT. The correlation between subjective xerostomia and both the stimulated and the unstimulated salivary secretion rate (USSR) was analyzed in children who had survived BMT for 2 years or more. The correlation between SGS time-activity curve variables and both the USSR and the SSSR was analyzed, and different regions for background correction were evaluated among children and adolescents treated for malignant, hematological, and metabolic diseases. Functional disturbances among long-term surviving children after total body irradiation (TBI) were analyzed using SGS.

A decreased SSSR was found during the first 6 months after BMT regardless of whether the conditioning regimen included TBI or not. One year after BMT, the SSSRs of the children who had only received chemotherapy exceeded baseline and continued to increase. The SSSRs of the TBI-treated group did not exceed baseline and 3 years after BMT no recovery was detected, indicating that salivary dysfunction in these children might be permanent. TBI-treated children exhibited significantly higher counts of mutans streptococci and lactobacilli 4 years after BMT compared to a healthy reference group. The prevalence of dental caries did not differ significantly between the reference group and the children surviving 4 years after BMT. No correlation was found between caries prevalence and salivary secretion rate and counts of caries-associated microorganisms in saliva. Significant risk factors for salivary dysfunction after pediatric BMT were conditioning with TBI, recipient female sex, and seropositivity for three to four herpes viruses. Subjective xerostomia was expressed by 79% of the long-term surviving pediatric BMT patients and was correlated with salivary gland dysfunction and age. That the function of the major salivary glands after TBI was impaired could be seen in the SGS by a trapping rate and emptying capacity that were lower than before BMT.

The results indicate that salivary dysfunction might be permanent after TBI at pediatric BMT. TBI, recipient female sex, and seropositivity for three to four herpes viruses are risk factors for salivary dysfunction after pediatric BMT. Subjective xerostomia is a frequent symptom among long-term survivors after BMT and is correlated with salivary dysfunction and age. Salivary dysfunction in TBI-treated children is portrayed by SGS as a reduction in both emptying capacity and trapping rate.